Unit heater and control mechanism therefor



4, 1934. R, H. NELSON 1mm HEATER AND CONTROL MECHANISM THEREFOR Filed Sept. T24, 1952 5 sheet-fsnaet 1- ardZ R. H. NELSON UNIT HEATER AND CONTROL MECHANISM THEREFOR Filed Sept. 24, 1932 5 sheets-sheaf, a

' Dee. 19341. I I NELSON 1,982,686

UNIT HEATER. AND- GORZEROL MECHANISM THEREFOR -Piled Sept. 24. 1932 5 sheets-shears;

Q m 3 l 4 ,za mer ZQEQM M1902 Dec. 4, 1934. R. H. NELSON UNIT HEATER ND CONTROL MECHANISM THEREFOR Filed Sept 24,, 1932 5 Sheets-Sheet 4 Dec. 4, 1934. R. H. NELSON mu'r HEATER AND cowrnoi; MECHANISM THEREFOR Filed Sept. 24, 1952 5 Sheets-Sheet 5 m? Q3 \m Patented Dec. 4, 1934 I v 1,982,636 J v UNIT HEATER AND CONTROL MECHANISM THEREFOR Richard H. Nelson, Moline "111i," assignor to The Herman Nelson Corporation, Moline, 111., a cornotation of Illinois i i i Application September 24, 1932,,S erialNo. 634,735

19 Claims. (01. 257-137) This invention relates to a unit-heater and ventilator of'the class commonly. employed-in school rooms, homes, or other places designed for human occupancy, under "conditions which fi necessitate the housing of the mechanical apparatus within'a compact cabinetof attractive appearance, and under conditionswhich require a relatively close regulation of the output of heated air.

' In particular, the present invention isdirected to the form an arrangement of the radiator and the means provided for regulating its heating'intensity, with a view of maintaining substantially uniform comfortable conditions within the room,

inconjun'ction with adamper of special form and arrangement, and controlling mechanisms therefor which areso inter-related with'theradiator controls as to co-operate in conjunction therewith in the maintenance of comfortableconditions.

0 Various efforts have heretofore been made to regulate the heating intensity oftheradiatonor radiators, employed in unit heaters, without complete success, however; and the present invention isdirected in part to the construction, location andmethod of controlling the radiator group in such a way as topermit variation in the extent of the heated radiating surface, but without introducing any inequality in the heatinglefiect, from end to end of the radiator ln otheri words; the construction is one in which eachportion ofthe unit, from end to end thereof,"will operate uniformly irrespective of the intensity of the heating effect or the number of radiator units in service at any particular time. d The invention furtherrelates to the utilization of a movable damper and filter so'arranged and located with respectto one another as to permit of a wide range of adjustment, without,.how ever, permitting the intrusion of cold outdoor air into theroom, and so arranged as to utilize the entire filter area for the passage of air in of damper adjustment.

n The working portions of the apparatus-are housed within a cabinet of special form and construction, which. however, constitutesWthe sub+ }ject of a co-pending application, Serial No. .626,-

403, filed July 30, 1932, for Heatingand ventilating units. I 1

In view of the fact that the present invention is not primarilyconcerned with the specific structure of the cabinet, it will-suflice to describe-the same only in general terins and in so far as conall positions cerns theoper'ation' of the features which" more. particularly fornithe subject matter ofjthe pr ent invention;

and a topor cover plate 13-. v

Inthe drawings: Figure 1 is a longitudinal elevation of the structure of the present invention showing the cabinet with the front panel removed to reveal the interior; 1

Fig-=2 is a top plan' view partly broken'away plateremoved to reveal the interior; I

Fig. 3 is an elevation showing one of the end doors removed to reveal the interior; Fig. 4 is asectional elevation taken on line 44 of-Fig. 1; I i i i Fig. '5' is -a sectional plan-view of the intake manifold for the radiator group;

Fig. 6 is a sectional elevation taken on line 6--6 ofFig.5; I Fig. 7 is across sectional viewoi' taken on line 7-- 7 of Fig. 6; i I

Figs. 8 and 9 aredetails of *the valve rod and in the center and with a portion of the top cover the manifold connections for operatingthe dampers;

nection for the valve of Fig. 10.

Thestructure as aywhole is housed within a cabinet which'comprises a rear wall 10, a removable front panel 11,.swinging -end doors 12 -12,

The swinging end doors are vertically pivoted on'hinges 14 to the rear wall 10, and the free edges of the doors are curved or bowed inwardly and configured to-provide marginal channels 15 provided each with a cushion strip 16 adapted to bear against the proximate edge of the front panel 11.

(The cover plate is provided around its margin with a depending flange 17 which serves to stiffen the plate and afford an attractive edge finish therefor. The cover plate is provided with four discharge apertures 18 into each of which is entered a fitting 19 provided with louvers 20, betweenjwhich theheated air is discharged and slightly deflected forwardly toward the interior end walls of an inner chamber 2'7, which may properly be referred to as the inlet chamber.

The inlet chamber communicates with an inlet duct 28 leading through the wall of the building, and within the inlet chamber is located an arch shaped filter 29, the lower edge of which rests within the channel bar 22 andthe upper edge of which abuts against the rear wall 10 of the cabinet immediately above the inlet duct.

Immediately below the inlet duct is located a rock shaft 30, which is journalled through the rear legs 25 of the end frames and carries a swinging damper 31, the forward edge of which is provided with a downturned flange 32, .which when the damper is swung inwardly to its extreme position will hook over the inner flange of the channel bar 22 (see Fig. 4).

The curvature of the filter 29 is concentric with the rock shaft 30, so that the free edge of the damper will swing in close proximity to the inner face of the filter, so that, irrespective of the adjustment of the damper, it will beimpossible for cold outside air, under'wind pressure, to-escape out of the base of the cabinet and into the room. Thus the entire area of the filter is at all times utilized for the admission of air from either or both of the intakes regardless of damper adjustment, so that at no stage is there an-increase 'in the resistance to the-flow of air. Ofcourse, after the air has been drawn through the filter,-further downward escape into the 'room is impossible, since the filter completely walls off the space above into which the air is drawn by the action of a fan presently to be described. I

The regulating damper 31 coacts with a group of three damper leaves 33, which are located within the inlet .duct28 andare each mounted upon a horizontal pintle 34.

Each of the. damper leaves 33 is provided with an inwardly extending "bracket 35, the brackets being -,connected by a :verticallyextending link 36. The intermediate bracket 35 is inwardly extended to afford an operating arm 3'7 which is connected bya link 38 with the controlling damper 31, so that a downward movement of the controlling damper 31, whichserves' to open the inlet duct for the admission of outdoor air, w.vvillbeaccornp an ied by an upward swinging movement of the three damper leaves to corresponding open positions, the arrangement being one inwhich the dampersswing in;opposition to one another, andanywind pressure that might tend to force the controlling damper inwardly to fully open position would be counteracted by the pressure of the wind on, thedamper leaves 33; the two damper mechanisms serving-to balance one another against the effects of v wind pressure.

The end frames 23 affordsupportfor the ends of a radiator assembly whichin its-entirety is designated by the numeral 39. The general configuration of the radiator assembly resembles that of a table top supported at its ends upon the end frames and overlying the inlet. chamber throughout practically its entire extent. The radiator assembly is relatively long and broad in the horizontal direction, and relatively shallow in the vertical direction, and of a width to completely fill the cabinet from the rear wall to the front panel.

The radiator assembly consists functionally of three independently operable radiator'sections, although in general structure it is a unit. As shown, each section is composed of; a group of three tubes 40, upon which are mounted a multiplicity of closely spaced radiating fins 41 to afford an extended radiating surface. The ends of the three groups of tubes are entered into a supply header 42 and a return header 43, which headers are of cast construction and rest upon and are supported by the end frames 23. Each of the headers 42 constitutes in effect three separately operable header sections which are divided from one another by partition walls 44, so that each group of three tubes with the associated header sections constitutes in eifect an independent radiator.

The intermediate section of the supply header 42 (see Fig. 5) is provided with an inner duct 45 which communicates with the right hand header section toadmit steam or other heating medium thereto, andin addition the intermediate header section isprovided with an inlet port 46, and the left hand section is provided with a similar port 47, the ports and the inlet end of the duct 45 being in closely spaced relation, and in communication with the inlet valve casing'48 which is bolted or otherwise rigidly secured to the outer wall of the header. The valve casing is provided with three ducts 49, 50'an'd 51', communicating respectively'with theduct 45 and the ports 46 and 47. The valve casing is'configured to provide a verticallyextending cylindrical body portion 52, with a branch 53 through which extend the ducts 49, 50 and 51.

1 Thebody of the'valve casing is cored to provide an inner'chamber 54 within which is located a tubular shell 55 provided with three restricted slots 56, 57 and 58, communicating respectively with the three ducts 49,' 50, and"'51'. The slots and the'a'ssociated ducts are arranged on different levels, the slot'58 occupying the lowermost level',"the slot 56 the intermediate level, and the slot 57the"highest"level.

Withinthe shell 55 is located a 'slidable valve 59 "which is carried'by a plunger rod 60 entered 115 through a cap 61' and'a gland 62 screw-threaded onto a nipple 63 of the cap. f The valve 59 is provided with a'plurality of vertically extending ports 64, and the valve casing is provided with a boss 65 into whichis' threaded'the main steam supply pipe66 whichcommunicateswith an inner lower chamber 67. Y I I 1 'The'arrangementis such that with the, valve in thelowermostpositioniirshown in Fig. 6,1.the steam admitted from' th'mainsupply pipe will be distributed'in equal amount to eachiof theheader sections;butas'the'valve is lifted, the port 58 will first be closed, and thereafteriin succession the ports 56 and 5'7, so that by successive adjustments of the valve, the steam supply will first 130 be shutoff from the left hand header,.then from the right hand header, and finally from the intermediate header. Thenthree. sections of the return header are likewise. in communication with three returnpipe sections. 68, each provided with 135 a trap 69 communicating with acommon header pipe 70 connected with a returnv line 771.

The plunger rod'60 isactuated bymeans of a thermostatic'motor '12 of any well known description; which'is 'lo'cated belowi ther'valve casing 48 4 assembly and through imparted in amplified degree to the rock shaft 30 'which controls the position of the dampers.

The radiator group serves to divide the cabinet through the middle and to afford an upper fan chamber '79 extending from end toend of the housing, and Within the fan chamber are located a group of fans (four in number) actuated by a common fan shaft 81 driven from a centrally disposed motor 82. The fans are supportedby legs 84 which carry a supporting rod 85 entered through aligned ears 86 on each of the fans.v Right angle brackets 87 are secured to the rear wall 10 of the cabinet, and extend forwardly therefrom and above the shaft 81,and serve'to support the top plate 13. The end frames 23 are located inwardly from the ends of the housing towafford lower 'end chamberswithin the swinging doors for the concealment of the piping and connections,while' the upper portion of the structure constituting. thefan chamber extends uninterruptedly fromend toend of the cabinet, thereby providing afan chamber greater in length than the radiator and inlet chamber 27, which is desirable in order.to.provide for the employment of a fangroup of relatively low velocity but of adequate capacityfor handling the volume of heated air delivered from the radiator assembly; This general arrangement enables the piping to be entirely concealedwithin the housing, andat the same time permits the. use of a housing; which is .not materially longer than should be used to house a, fan assembly of.,.the most desirable character.

The lower end chambers for thepiping. are walled 011' from the ends of the fan chamber by the provisionxof partition plates 881whichextend outwardly from the ends of the radiators .to the degree required to make contact with, the swinging doors when closed, so that in operation the in,- terior of the cabinet will be divided into separated chambers properly located to afford a passage way for the air, either upwardly through, thebase of the cabinet, or inwardly throughthe, fresh air duct, and thence upwardly through, the radiator, the fansto the point of discharge; 1 1 3. I v l" a In order to assist in cooling the motor 82, the t p plate is provided .with -sajc ntrallyidisp s aperture 89, which admits air downw r ll around} the motor and into thewadjacent fansg; thereby maintaining a cooling circulation of airat this point.

The alternate form of construction shown in Figs. 10 and 11 is designed particularly. for use in cases where the temperature controlequipment affords very little power and where, the sl ide', valve arrangement previously described might; have a tendency to stick or bind, so that a more easily operable form of construction might be desirable. In this instance, the inlet header, is divided into three sections, 90;-91-, 92, similar to those previously described. Thesection 91 is served by a direct centrally disposed -passage;;93;- the section 90 by a lower passage-94, an section92 by-an upper passage-95 a; i

The three passages stand in register withpase; sages 96, 97, 98, respectively, throughiithe; neck-r: 99 of a valve casing 100; and the latterthreeypasel sages communicate respectively "with "charnbe 101, 102, 103, in the valve casing, whichwchamtiersr are defined by cross walls 104,105, 106, arranged-ii respectively at ascending levels in the valve cas The respective cross walls are provided with beveled valve seats 107, 108, 109, of progressively increasing diameter, which valve seats coact with sively increasing size.

The'lower portion of the valve casing furnishes an admission chamber 113 to which steam is suppliedthrough'a port 114. The capacity of the respective valve openings is such that the lowermost opening will be of an area adequate to supply steam to all three of the header sections,- the-middle opening to two of the header sections, and the-'upperj-opening to only a single one of the hea-tlei sections.

All three of the valves are mounted upon a verticall y'slidable valve stem 115, which is entered through a: plug'l16 and a gland 117. The valve stem is shouldered at the point 118, and the three valvs" are*freelycarried on the reduced and of the 'stemand are held in separated relation by coil'springs 119-120, the uppermost valve being held'in place by across pin 121. The springs serve to normally hold the'three valves in position on the reduced end of the valve stems and at varying distances fromthe respective valve seats, the uppermost valve being held nearest to its seat, andthe two remaining valves at progressively greater distances from their respective seats.

As the valve stem is vertically adjusted, the uppermost valve 121 will first be seated on its seat 107, and thereafter the middle valve 111 will be seated, and ultimately the lower valve as the adjusting movement continues. Thus, by a continued movement upward, the three valves will be successively seated and serve to progressively close off the steam supply to the three header sections, the coil springs permitting con- Wi'th t e dampers occupying this adjustment,

the yalve-59 (or the valves 110F111, 112, as the case may be) will" occupy the'fu'lly open position, so that steam will be admitted to all three sections of the radiator assembly, and the maximum heating effect of recirculated indoor air will be secured. This represents a condition in which the "room temperature is belowthe controlling range for the thermostat; which preferably-affords the basis of control for the mechanism. As the room temperature rises to a point which begins to actuate the thermostat, pressure will be admitted to the motor in a manner well understood in the art, and this will have the effect of moving the plunger rod 60 (or 115) through 1 varying degrees of adjustment, under thermostatic control. I

he movem'ent of the valve be slight, it may have heefiect of closing the first of the three slotted apertures for admitting steam to the members of the radiator assembly, which will have the efiect of closing 011 one of the radiator sections-and thus reducing the intensity of the heating'efl'ect, without, however, disturbing the action of the remaining radiator sections. A

: further increase in the room temperature will move the plunger and valve to the second position, thereby cutting 011 the intermediate radiator section and ultimately cutting off the forward section, without, however, up to this stage affecting the adjustment of the dampers which still remain-closed against the admission of outdoor air.

After the heat has been completely shut off, a continued rise in temperature, with resultant continued movement of the plunger rod, will begin to actuate the dampers through the link and lever mechanism shown, and this damper adjustment may continue through intermediate stages, until the dampers are thrown to the completely open position indicated in Fig. 4, at which point the recirculation of indoor air is completely prevented, and the entire supply of air is taken from out of doors.

The pin and slot connection for the bifurcated end of the lever 74 affords sufficient lost motion in the movement of the plunger rod to postpone the operation of the dampers until after the radiator sections have all been turned off, but it will be understood that these operations may occur either sequentially or concurrently, or by any degree of overlap which may be desired or required to meet local conditions, so that it is not the intention, in all cases, to completely defer the damper adjustments until after the steam or other heating medium has been completely shut off from the radiator group.

This grouping of the radiator sections is one which enables each section to operate perfectly as a complete unit, so that an equalized heating effect will be secured from end to end of the radiator section, or sections, as the case may be, and so that one end of the cabinet will not be heated in excess of the other, although the intensity of the heating will, of course, depend upon the number of sections in service, as well as upon the steam pressures employed.

By utilizing relatively shallow radiator sections, there will be little if any opportunity for the steam to travel in oblique channels through the radiator, so that all portions of the radiator section will be equally heated throughout, andmultiplication of this arrangement in group form permits of the regulation under thermostatic control of the heating effect throughout a considerable rang in degrees, which is highly desirable in order to closely maintain a predetermined comfortable temperature range within the room.

Moreover, the radiator assembly is one which completely fills the cabinet from front to rear thereof, and the controlling of the steam supply to one or more of the radiator sections obviates the necessity for providing a by-pass for cold air, which is wasteful of space, and in present constructions tends to increase both the width and height of the unit.

Furthermore, although structurally considered the radiator assembly is practically a unit, nevertheless, in operation the sections constitute independent radiators which can be adequately controlled by valve means of the character described, which does not require the use of small openings or precise adjustments, and which may remain sufficiently rugged in construction to withstand the burden of actual usage without danger of impairment. This is particularly important in view of the fact that previous attempts to control the heat output by throttling the steam supply to the radiator have not been successful because the openings are necessarily so small that they tend to clog easily, and because control devices designed to effect minute adjustments are entirely too fragile for actual service.

The arrangement of the controlling, damper with respect to the filter is such as to prevent cold air escaping through the base of the cabinet, irrespective of the adjustment of the damper, since in all cases the entire area of the filter will be exposed to the incoming air from whichsoever source, the relative exposure to the indoor and outdoor air being determined in all cases by the position of the controlling damper. Even under windy conditions, there can be no possibility of back 5 draft, since after the air is once drawn through the filter, the filter will present a suflicient obstacle to its return and discharge into the room through the recirculation inlet, particularly when the air is constantly subjected to the suction of the fan group above.

Although the filter, in conjunction with the damper, affords a most desirable obstacle to the back draft of outdoor air, nevertheless, the principle indicated is one which is not limited to the employment of a filter, since any other form of impediment similarly located in coacting relation with the edge of the damper would subserve a like purpose in guarding against back draft admission of outdoor air. In fact, the principle involved is one which might find embodiment in a suitable dispositionbf the radiator itself to afford the obstructive element necessary to prevent such back draft.

The structure as a whole is one which locates the operating parts in compact arrangement with respect to one another, and enables them to be housed in a cabinet of relatively small dimensions, and at the same time affords a direct line of upward travel for the air from the point of ingress to the point of discharge, so that excessive pressure on the fans is avoided.

Furthermore, the arrangement is one which enables convenient access to be had to all portions of the interior and enables the piping to be 115 brought into a relatively small compass.

Although the invention hasbeen described with particularity as to detail, it is not the intention to limit the invention to the arrangement shown, since the principles involved may be embodied 120 in other forms of construction without departing from the principles of the invention.

It will also be understood that although the invention has been particularly described as a radiator for heating purposes, I have in con- 125 templation the use of the apparatus for cooling purposes, so that in the claims and elsewhere, where mention is made of the admission of a heating medium, such terms are intended to include the use of a cooling medium where it is desired to use the apparatus for cooling rather than for heating purposes.

I claim:

1. In a device of the class described, the combination of a cabinet having an inlet for recirculation of room air and an inlet for the admission of exterior air, a controlling damper hinged in position to close either of said inlets and to be moved and held in intermediate positions of adjustment, an obstructive element adapted to permit air to be drawn therethrough and of arcuate configuration occupying a position closely adjacent to the path of movement of the edge of the controlling damper and adapted to coact therewith in directing air from either or both sources inwardly into the cabinet and in preventing exterior air from passing through the recirculation inlet and into the room when the damper stands in an intermediate position, and a fan beyond said obstructive element for suck- 150 ing in air from either or both of said inlets and through the obstructive element.

2. In a device of the class described, the combination of a cabinet having an inlet for recirculation of room air and an inlet for the admission of exterior air, a controlling damper hinged in position to close either of said inlets andito be moved and held in intermediate positions of adjustment, an obstructive element adapted to permit air to be drawn therethrough and of arcuate configuration, occupying a position closely adjacent to the path of movement of the edge of the controlling damper and adapted to coact'therewith in directing air from either or both sources inwardly into the cabinet and in preventing exterior air from passing through the recirculationinlet and into the room whenthe damper stands in an intermediate position, a fan beyond said obstructive element for sucking in air from either or both of said inlets and through the obstructive element, an inlet damper in the exterior air inlet, and connections between said inlet damper and said controlling damper for causing the two dampers to move in reverse relation to one another in opening and closing the inlet for exterior air.

3. In mechanism of the class described, the combination of a cabinet provided with a recirculation air inlet in its base and with an exterior air inlet in its rear wall, a controlling damper hinged between the two inlets and adapted to swing from closing position of one of the inlets to closing position of the other inlet and adapted to stand in intermediate positions of adjustment, a filter within the cabinet, of arcuate formation and of a curvature to present its inner surface into close relation to the edge of the swinging damper in all positions of damperadjustment, and a fan beyond the filter for drawing air therethrough from either or both of said inlets and discharging the same into the room.

4. In mechanism of the class described, the combination of a cabinet provided with a recirculation air inlet in its base and with an exterior air inlet in its rear wall, a controlling damper hinged between the two inlets and adapted to swing from closing position of one of the inlets to closing position of the otherinlet and adapted to stand in intermediate positions of adjustment,

a filter within the cabinet, ofparcu'ate formation and of a curvature to present its inner surface into close relation to'the edge of the swinging damper in all positions of damper adjustment, a fan beyond the filter for drawing air therethrough from either or both of said inlets and discharging the same into the room, and radiating means interposed between the filter and the fan.

5. In mechanism of the class described, the

combination of a cabinet provided with a recirculation air inlet inlits base and with an exterior air inlet in its rear wall, a controlling damper hinged between the two inletsand adapted to swing from closing position of one of the inlets to closing position of the other inletand through intermediate positions of adjustment, a filter within the cabinet, of arcuate formationand of a curvature to present its innersurface into close relation to the edge of the swinging damper, a fan beyond the filter for drawing air therethrough from either of said inlets and discharging the same into the room, and radiating means interposed between the filter and the fan, said radiating means being composed of a plurality of radiators, each comprising a group of radiating elements, a supply header commonto the groups of radiating elements, said supply header being divided into sections, one for each group .of radiating elements, return connections for the respective groups of radiatingelements, and valve means common to the supply header sections for controlling the admission of a heating medium to one or more of said sections, and connections air inlet in its rear wall, a controlling damper hinged between the two inlets and adapted to swing from closing position of one of the inlets to closing position of the other inlet and through intermediate positions of adjustment, a filter within the cabinet, of 'arcuate formation and of valve means for controlling a supply of said heating medium to one or more of said groups of radiating elements, and connections between said valve means and movable therewith for actuating .said controlling damper in harmonized relation to said'valve movements and for correlating the damper adjustment to' the heating in ensity of the mechanism. i v

8. In mechanism of the class described, the

combination of a cabinet provided with an inlet for recirculating room air and an adjacent inlet for admitting exterior air, a swinging damper hinged between said inlets and adapted to be' moved from closing position for one of said inlets to closing position for the'other of said inlets and through intermediate positions of adjustment,

radiating means comprising a plurality of groups of radiating elements, means for supplying a heating medium to said groups of radiating elements, valve means for controlling a.supply of said heating medium to one or more of said groups of radiating elements, and connections between said valve means and movable therewith for actuating said controlling damper in harmonized relation to said valve movements and for correlating the damper adjustment to the heating intensity of the mechanism, said connections being adapted to maintain the controlling damper in position to close the exterior air inlet against the admission of exterior air during the period when the heating medium is admitted to all of the groups of radiating elements, and adapted to close the re-circulation air inlet against the re-circulation of room air when the heating medium is excluded from all of the groups of radiating elements.

9. In mechanism of the class described, the combination of a cabinet provided in its base with a recirculation air inlet for room air and provided in its back wall with an exterior air inlet, a swinging damper hinged intermediate the two inlets, and adaptedfiin one extreme position of adjustment to close the recirculation air inlet and in the other extreme position of adjustment to close the exterior air inlet and to occupy intermediate positions or adjustment, radiating means extending from the iront to the rear wall of the cabinet above the inlets and divided into groups of radiating elements, a supply header common to the groups of radiating elements and a return header common to the groups of radiating elements, the supply header and the return header being each divided into separated sections, one section for each group of radiating elements, and means for admitting a heating medium to the sections of the supply header, valve means for controlling the supply of said heating medium to one or more of the sections of the supply header, return connections for the respective sections of the return header, connections between said valve means and said damper for correlating the movements of the damper to the supplying of the heating medium to the radiator sections, and a fan within the cabinet above the radiating means for drawing air therethrough and discharging the same into the room.

10. In mechanism of the class described, the combination of a cabinet provided in its base with a recirculation air inlet for room air and provided in its back wall with an exterior air inlet, a swinging damper hinged intermediate the two inlets, and adapted in one extreme position of adjustment to close the recirculation air inlet and in the other extreme position of adjustment to close the exterior air inlet and to. occupy intermediate positions of adjustment, radiating means extending from the front to the rear wall of the cabinet above the inlets and divided into groups of radiating elements, a supply header common to the groups of radiating elements and a return header common to the groups of radiating elements, the supply header and the return header being each divided into separated sections, one section for each group of radiating elements, and means for admitting a heating medium to the sections of the supply header, valve means for controlling the supply of said heating medium to one or more of the sections of the supply header, return connections for the respective sections of the return header, connections between said valve means and said damper for correlating the movements of the damper to the supplying of the heating medium to the radiator sections, a fan within the cabinet above the radiating means for drawing air therethrough and discharging the same into the room, and a filter of arcuate formation interposed between the damper and the radiating means and in a position to lie closely adjacent to the path of movement of the free edge of the damper to prevent cold exterior air being forced through the recirculation inlet.

11. In mechanism of the class described, the combination of a cabinet, a fan located in the upper portion of the cabinet and in position to discharge air upwardly into the room, radiating means extending transversely from front to rear of the cabinet and located below the fan, said radiating means comprising groups of radiating elements and header connections therefor, each group with its header connections constituting a complete radiator, means for supplying a heating medium to said radiators, valve means for controlling the supply of heating medium to one or more of said radiators, an inlet for recirculation of room air and an inlet for exterior air, and a damper common to the two inlets and adapted to control the proportionate volume of air admitted through each inlet, and connections between said valve and said damper for correlating the movements of the damper to the supplying of heating medium to the radiators.

12. In mechanism of the class described, the combination of a cabinet, a fan located in the upper portion of the cabinet and in position to discharge air upwardly into the room, radiating means extending transversely from front to rear of the cabinet and located below the fan, said radiating means comprising groups of radiating elements and header connections therefor, each group with its header connections constituting a complete radiator, means for supplying a heating medium to said radiators, valve means for controlling the supply of heating medium to one or more of said radiators, an inlet for recirculation of room air and an inlet'for exterior air, and a damper common to the two inlets and adapted to control the proportionate volume of air admitted through each inlet, and connections between said valve and said damper for correlating the movements of the damper to the supplying of heating medium to the radiators, said connections being adapted to hold the damper in position to close the re-circulation air inlet when heating medium is excluded from all of the radiators and to hold the damper in position to exclude exterior air when the heating medium is admitted to all of the radiators.

13. In a device of the class described, the combination of a cabinet having an inlet for re-circulation of room air and an inlet for the admission of exterior air, a controlling damper movable to close either of said inlets and to stand in intermediate positions of adjustment, an obstructive element adapted to permit air to be drawn therethrough and occupying a position closely adjacent to the path of movement of the edge of the controlling damper and adapted to coact therewith in directing air from either or both sources inwardly into the cabinet and in preventing exterior air from escaping through the recirculation inlet and into the room in all positions of damper adjustment, and a fan beyond said obstructive element for sucking in air from either or both of said inlets and through the obstructive element, the area of said obstructive element available tor the inflow of air being uniform throughout all damper adjustments.

14. In mechanism of the class described, the combination of a cabinet having an inlet for recirculation of room air and an inlet for the admission of exterior air, a controlling damper located between the respective inlets and movable to close either of said inlets and to stand in intermediate positions of adjustment, a filter within the cabinet positioned to present its surface into close relation to the edge of the damper to prevent escape of exterior air through the recirculation air inlet in all positions of damper adjustment, and a fan beyond the filter for drawing air therethrough from either or both of said inlets, the'area of said filter available for the inflow of air being uniform irrespective of the damper adjustment maintained.

15. In a device of the class described, the combination of a cabinet having an inlet for recirculation of room air and an inlet for the admission of exterior air, an obstructive element positioned to permit the passage therethrough of air admitted through either or both of said inlets, and a partition located between the respective inlets and adjustable to varying posit.ons with relation to the obstructive element, said adjustments serving to expose varying proportionate areas of the obstructive element for the passage of air from the respective inlets depending upon the adjustment maintained.

16. In a device or the class described, the combination of a cabinet having an inlet for recirculation of room air and an inlet for the admission of exterior air, an obstructive element positioned to permit the passage therethrough of air admitted through either or both of said inlets,-

and a partition located between the respective inlets andmovable with relation to the obstructive element and adapted in conjunction therewith to prevent the direct passage of air from the exterior air inlet to the interior air inlet, said movement of the partition serving to expose and maintain the desired proportionate areas of the obstructive element for the passage of air from the respective inlets.

17. In mechanism of the class described, the combination of a cabinet having an inlet for recirculation of room air and an inlet for the admission of exterior air, a controlling damper located between the respective inlets and movable to close either of said inlets and to stand in intermediate positions of adjustment, a filter within the cabinet positioned to present its surface into close relation to the edge of the damper to prevent escape of exterior air through the recirculation air inlet in varying positions of damper adjustment, and a fan beyond the filter for drawing air therethrough from either of said inlets, the area of said filter available for the inflow of air being uniform throughout all damper adjustments.

18. In a device of the class described, the combination of a cabinet having an inlet for recirculation of room air and an inlet for the admission of exterior air, an obstructive element positioned to permit the passage therethrough of air admitted through either or both of said inlets, and a partition located between the respective inlets and movable in close relation to the obstructive element, said movement serving to expose and 100 maintain the desired proportionate areas of the obstructive element for the passage of air from the respective inlets.

19. In a device of the class described, the combination of a cabinet having an inlet for recirculation of room air and an inlet for the admission of exterior air, an obstructive element positioned to permit the passage therethrough of air admitted through either or both of said inlets, and a partition located between the respective inlets 110 and movable in close relation to the obstructive element and adapted in conjunction therewith to prevent the direct passage of air from the exterior air inlet to the interior air inlet, said movement of the partition serving to expose and 115 maintain the desired proportionate areas of the obstructive element for the passage of air from the respective inlets.

' RICHARD H. NELSON. 

